Abstract: This paper proposed an intelligent wireless indoor monitoring system based on STM32F103. The system compromises a master and terminals, which communicates through a CC1101 433M wireless unit. Using ENC28J60 and SIM900A to access Ethernet, the system can intelligent push information to cloud server, therefore we can observe and control terminals remotely. This paper present an algorithm based on MCU ID for terminal code recognition. The algorithm can intelligently discriminate terminals through code matching code between master and terminals, though hardware and software of terminals is similar. The experiment demonstrates that the proposed system is robust stability, real-time and obtains accurate warning information.